Sync OpenBSD patchset 427:
Sync OpenBSD patchset 427:

Don't redraw the scroll region on linefeed/reverse index unless it is necessary
(the cursor is at the bottom/top). Should fix slow cursor movement when using
vi in a pane spotted by pirofti@.


klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux